Rapid diagnosis of coagulopathies from vitamin K deficiency in a consecutive case cohort evaluated by comparative assessment of factor II by 1-stage assays with prothrombin time vs Ecarin reagents

BACKGROUND: Vitamin K (VK) deficiency (VKD) impairs γ-carboxylation of VK-dependent factors (VKDFs), resulting in higher factor (F)II levels measured by Ecarin (FIIE) reagents (that convert des-γ-carboxylated FII to meizothrombin) than by prothrombin time (FII) reagents. OBJECTIVES: To evaluate FII/FIIE abnormalities among patients assessed for coagulopathies and identify findings predictive of coagulopathy improvement after VK. METHODS: We retrospectively assessed consecutive cases from 2002 to 2021 with FII/FIIE tests and the sensitivity and specificity of FII/FIIE ratios and FIIE-FII differences for VKD defined as international normalized ratio correction/improvement of ≥0.5 after VK. RESULTS: Two hundred ninety-two patients (males, 58.2%; adults, 85.6%; median age, 73 years) were evaluated (84.2% hospitalized, 48.3% in intensive care, 71.6% with active liver disease, and 28% deceased at discharge) and 25% to 38% had FII/FIIE findings suggestive of VKD. Among 170 patients assessed for response to VK, FII/FIIE ratios of ≤0.84 to 0.91 and FIIE-FII differences of >0.04 U/mL had similar modest sensitivity (47.7%-69.3%) and modest to good specificity (67.1%-91.5%) for VKD. FII/FIIE ratios of <0.86, suggestive of VKD (sensitivity, 47.7%; specificity, 90.2%), were more common in patients deficient in only VKDF (P = .0001), but were detected in 16% with non-VKDF deficiencies. Low FIIE was commonly associated with active liver disease (P = .0002). Patients with and without probable VKD (based on FII/FIIE ratios of <0.86) had similar mortality, bleeding, and rates of prothrombin complex concentrate and red cell transfusions (P ≥ .78), but fewer with probable VKD received plasma and fibrinogen replacement (P ≤ .024). CONCLUSION: FII/FIIE comparison aids the diagnosis of VKD and predicts clinical responses to VK treatment among patients with coagulopathies.